In the four years since we and the others first observed that consumption of choline or lecithin raised brain acetylcholine levels in rats, these neurotransmitter precursors have been used successfully to treat one psychiatric disease, tardive dyskinesia, and tried in a few patients with other diseases (Mania; memory disorders). We are undertaking a program of research, involving humans and experimental animals, designed to increase our fundamental understanding of lecithin's effects, and to apply this knowledge to clinical problems. One set of studies explores the fate of ingested lecithins, and examines the contributions of various choline sources to blood choline; a second studies the origins of brain choline (e.g., carrier-mediated uptake from the blood; endogenous lecithin biosynthesis); a third examines some psychopharmacological effects of choline (e.g., on animal behaviors; its interactions with lithium and with opiate agonists; relations between choline's effectiveness and neuronal firing rates; possible feedback regulation of elective lecithin consumption). Clinical experiments examine the clinical utility of choline/lecithin in psychiatric diseases (pilot studies on mania and on memory disorders); the effects of various phosphatide preparations (e.g., egg vs soy lecithin) on blood choline levels in normal subjects; and the quantities of dietary choline needed to induce daily rhythms in plasma choline.